i tried it
IMO,
i wouldn't risk it. guppies or any fish with large colorful plummage can trigger some betas to attack. but like others say, it all depends on your beta. i put my beta, which i had for 5 years, into a community tank with sailfin mollies and guppies and it literally flared up and attacked them to a point where i had to take him out. it might work, i just wouldnt risk it